[GHC] #8557: Panic "tcTyVarDetails" when :forcing a kind-polymorphic data family instance

[GHC]

#8557: Panic "tcTyVarDetails" when :forcing a kind-polymorphic data family
instance
-------------------------------------+------------------------------------
        Reporter:  goldfire          |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.7
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
-------------------------------------+------------------------------------

Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"a8ac471d435214dbdc1fa70f938c63128993a1db/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="a8ac471d435214dbdc1fa70f938c63128993a1db"
 Fix the deugger (fixing Trac #8557)

 The runtime debugger (which has not received any love from anyone
 for many years) looks wrong to me; it was failing to instantiate the
 outer foralls of a variable when called from :force, which calls
 cvObtainTermFromId, which calls cvObtainTerm

 I simplified the code too.  But I'm flaky on how this debugger stuff
 is really supposed to work, so I'm partly guessing.  Tests pass though.
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8557#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler